A US naval base at Sasebo, in western Japan, was put on lockdown on Thursday after reports of gunshots, a Navy spokesman said, but there was no confirmation of an active shooter.

Gunshots had been reported from a building on the base, 980 km (614 miles) west of Tokyo, and the base was put on lockdown as a precaution as the building was checked by security, said Darin Wilson, Deputy Public Affairs Officer for U.S. Naval Forces, Japan.